Re: Trigger electrode wear

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

Gary,

The problem is that the main discharge in a trigatron does end up going
from one electrode, through the trigger electrode, to the other
electrode. This does cause trigger electrode erosion, and this is one of
the failure modes for trigatrons. As long as the trigger electrode can
be easily replaced, you don't need to use tungsten. But tungsten should
result in less maintenance. 

Triggering can be done in any of the quadrants - some quadrants are
simply a bit more consistent. As long as you have sufficient triggering
voltage to reliably fire the gap, the minor amount of jitter shouldn't
be a problem. A small amount of jitter should have virtually no impact
on the tank capacitor bang to bang energy when the gap actually fires. 

Best regards,

-- Bert -- 
-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com



Tesla list wrote:
> 
> Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Gary.Lau-at-compaq-dot-com>
> 
> My progress on a triggered spark gap may only be described as "glacial",
> but I am making progress.  It seems as if most of the ones built to date
> have the trigger electrode located midway between the two main electrodes.
> When the main gap fires, the high-current arc passes through the trigger
> electrode in two separate segments.  In addition to the trigger electrode
> enduring the full power of the main arc, it would seem as the gap losses in
> such a multi-segment arc may be higher.
> 
> I'm wondering if the trigatron geometry, where the trigger electrode is
> coaxial and flush with one of the main electrodes, would be better so far
> as trigger electrode erosion goes?  I'm just trying to decide if I need to
> find tungsten rods, or if any kind of wire or threaded rod would suffice.
> If it only has to endure the relatively low energy pumped into the trigger
> coil, i.e. if the main arc does not pass through the trigger electrode,
> there should be almost no erosion.  Does it?
> 
> My only reservation with the trigatron geometry is that the trigger
> polarity with respect to the adjacent electrode is always the same, since
> I'm using a DC-powered trigger generator. This results in alternate trigger
> polarities with respect to the main electrode biases on alternate
> half-cycles.  Is this only significant if nanosecond-level jitter is a
concern?
> 
> Regards, Gary Lau
> MA, USA

-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com